a.tooltip
    { 
    position:relative;
     z-index:24;
      }
     a.tooltip:hover
     {z-index:25;
     }
     a.tooltip span
     {
     display: none
     }

     a.tooltip:hover span
     { 
   
     display:block;position:absolute; top:2em; left:2em; width:15em; border:1px solid #000000; background-color:#FFFFFF; color: #000000; text-decoration: none;  text-align: center; font-weight:bold; padding: 10px 10px 10px 10px;
     }